Nowadays I primarily do backend development, because I'm fascinated by complex mathematical algorithms. One example of such code is my steganography tool enabling you to conceal any file within a PNG file. The only frontend development I do is web development like my homepage, which is written in pure HTML, CSS, and JS. Or for school, I create presentations like this one using reveal.js.
I use multiple operating systems at the same time. As my main OSs, I use Arch Linux and Gentoo Linux, while I depend on Windows 10 for music production and other Windows-specific tasks. On my Linode instance, I'm running Debian 10 “Buster”.
Apart from the wide range of operating systems, I also got into server administration about a year ago. The same server, that this website is hosted on using NGINX, also serves as a Nextcloud server, an SSH/SFTP server, a Git server, a Matomo Analytics server, an Onion Service, and even a Minecraft server (although I don't play myself).
I'm still new to containerization, but I do have some experience with Docker.
Having my own webserver also means that I have to protect it against external cybersecurity threats. At one point in time my Linode was actually being targeted by bots, which caused increased traffic and an unstable webserver, so several security measures had to be implemented.
I also have quite a bit of experience with Kali Linux and some of its pentesting tools, such as Metasploit, Hydra, HashCat, Wireshark, and Aircrack-ng.